A hard disk is a storage device employed in personal computers, hard disk drive (hereinafter simply HDD) recorders, and the like. Storage density of the hard disk is increasing year after year.
To realize further improvement in storage density, the recording system is switched from longitudinal recording to vertical magnetic recording in recent years.
In addition, for the further improvement in storage density, research and development on various media, such as Discrete Track Media (DTMs) and Bit Patterned Media (BPMs) have been actively conducted.
FIG. 14 is a schematic plan view of an arrangement of data tracks and servo patterns in a general DTM. FIG. 15 is a schematic partial cutaway view illustrating a positional relation of tracks and guard bands in a general DTM.
A DTM 200 depicted in FIG. 14 has tracks 203 and guard bands 204 magnetically separating adjacent tracks 203. The tracks 203 and the guard bands 204 are alternately and concentrically disposed. The tracks 203 include a plurality of data tracks 201 and servo patterns 202. Data can be written into the data track 201 and reproduced therefrom. The servo pattern 202 is disposed between the data tracks 201 to allow reproduction of positional information of the data track 201.
In the DTM 200 depicted in FIG. 15, the guard bands 204 each magnetically separating adjacent tracks 203 are disposed to suppress side erase of the adjacent track 203 corresponding to the guard band 204, thereby achieving an improved storage density by physical shape of grooves.
FIG. 16 is a schematic partial cutaway view illustrating an arrangement of tracks and a guard band in a general BPM.
A BPM 210 depicted in FIG. 16 is configured to have discontinuous data tracks 212 not only magnetically separating adjacent tracks 211 in a track direction but also magnetically separating them in a down track direction, that is, in a bit longitudinal direction, thereby improving not only tracking density but also bit density.
The conventional HDD device includes a magnetic head unit provided with a storage element and a reproducing element. The storage element writes data in a data track of a mounted magnetic storage medium, and the reproducing element reproduces data written in the data track. A distance between the storage element and the reproducing element is several tens of micrometers.
In the conventional HDD device, the mounted magnetic storage medium is formed of a magnetic recording layer of continuous film. Thus, after the storage element writes offset measurement data into the magnetic storage medium, the magnetic head unit is moved in a track direction to make the reproducing element reproduce and output the data. An amount (distance) shifted from a write position where the offset measurement data is written to a reproduction position at which the reproduction output is at maximum is determined as an offset amount between the reproducing element and the storage element.
Therefore, the reproducing element and the storage element can be smoothly positioned with respect to the data tracks based on the offset amount between the reproducing element and the storage element in the conventional HDD device (for example, refer to Japanese Laid-open Patent Publication No. 09-45025).
According to the conventional HDD device, in a magnetic recording medium including a magnetic recording layer of continuous film, after offset measurement data is written in a data track, the magnetic head unit is moved in a track direction to reproduce and output data through the reproducing element, and then a distance from a write position where the offset measurement data is written to a reproduction position at which the reproduction output is at maximum is determined as an offset amount between the reproducing element and the storage element. However, in a magnetic recording medium, such as a DTM or BPM, the track position of the data tracks is fixed, and guard bands are present between adjacent tracks. Therefore, the offset measurement data is required to be reliably written at the center of the data track.
Therefore, according to the conventional HDD device, it is difficult to determine an offset amount between the storage element and the reproducing element of the magnetic head unit for the magnetic storage medium with a guard band between adjacent tracks, such as a DTM or BPM.